Hydraulically powered gripping tool

Abstract

A hydraulic operated tool includes a body (B), a pair of jaws ( 21 ) mounted with respect to the body so that at least one of the jaws is movable between an opened jaw position and a closed jaw position so as to engage workpiece (W) between the jaws. A ram assembly ( 2 ) is disposed in the body and is operatively associated with the jaws. Spring structure ( 1 ) causes the ram assembly to move thereby causing the jaws to initially engage the workpiece with a first force. A pump assembly ( 7 ) exerts fluid on the ram assembly to move the ram assembly further, causing the jaws to exert a second force, greater than the first force, on the workpiece.

1. A hydraulically powered and operated tool comprising:
 a body, 
 a trigger mounted for movement between first and second positions with respect to the body, 
 a pair of jaws mounted with respect to the body so that at least one of the jaws is movable between an opened jaw position and a closed jaw position so as to engage work between the jaws, 
 jaw actuating structure associated with the at least one jaw to cause movement of the at least one jaw, 
 a ram assembly having first and second ends and including a valve actuating structure and a ram piston, the valve actuating structure having first and second ends, the first end of the ram assembly being coupled with the jaw actuating structure, 
 a first check valve associated with the ram piston, 
 a second check valve associated with the ram piston and with the second end of the valve actuating structure, 
 a lever associated with the first end of the valve actuating structure and with the ram assembly, 
 surfaces defining a cavity in the body, the cavity having hydraulic fluid therein, the ram piston being disposed in the cavity separating the cavity to define a ram chamber and a reservoir chamber, 
 spring structure engaging a second end of the ram assembly, and 
 a pump assembly operatively associated with the trigger to be movable between a first position, when the trigger is in the first position, and a second position when the trigger is in a second position, the pump assembly having a pump chamber in selective fluid communication with the ram chamber and the reservoir chamber, 
 whereby, 1) when the lever is moved to an activated position, the valve actuating structure unseats the second check valve permitting fluid to flow from the ram chamber to the reservoir chamber, with the ram assembly displacing fluid as it compresses the spring structure and causes the jaw actuating structure to move the at least one jaw so work can be placed between the jaws, and 2) when the lever is released from the activated position, the second check valve is seated and the spring structure drives the ram assembly to an extended position causing the jaw actuating structure to move the at least one jaw so the jaws engage the work, with the first check valve being unseated by fluid pressure in the reservoir chamber, permitting fluid to flow from the reservoir chamber to the ram chamber, and 3) when the trigger is moved from the first position to the second position, the pump assembly moves to the second position thereof and forces fluid from the pump chamber into the ram chamber causing the first check valve to seat, with the forced fluid being exerted on the ram piston, increasing force of the jaws on the work. 
 
   
   
     2. The tool of  claim 1 , wherein the valve actuating structure is a push rod and the second check valve includes a valve member associated with the ram piston, such that when the lever is moved to engage the push rod, the push rod moves and unseats the valve member permitting fluid to flow past the ram piston, and when the lever is released, a spring biases the valve member to the seated position. 
   
   
     3. The tool of  claim 1 , wherein the pump assembly includes:
 a pump piston in the pump chamber, the pump piston having a first diameter portion and a second diameter portion that is larger than the first diameter portion, the trigger being connected to the pump piston, and 
 a third check valve, permitting when unseated, fluid to flow from the reservoir chamber to the pump chamber, and when seated, preventing fluid flow from the pump chamber to the reservoir chamber, 
 whereby, as the trigger is moved to the second position, the pump chamber changes volume due to the second diameter portion of the pump piston replacing the first diameter portion in the pump chamber, causing fluid to be forced into the ram chamber, and when the trigger is moved to the first position, fluid moves from the reservoir chamber to the pump chamber. 
 
   
   
     4. The tool of  claim 1 , wherein the ram piston is movably disposed in a bore in the body, and wherein the first check valve includes an O-ring disposed between a peripheral surface of the ram piston and surfaces defining the bore. 
   
   
     5. The tool of  claim 1 , wherein the jaw actuating structure includes a gear rack and first and second gear segments, the gear rack being coupled with the ram assembly, the first gear segment being engaged with the gear rack, the second gear segment being associated with at least one of the jaws, the first and second gear seconds being engaged with each other such that movement of the gear rack moves the at least one jaw. 
   
   
     6. The tool of  claim 3 , further including at least one link connecting the pump piston to the trigger. 
   
   
     7. The tool of  claim 1 , wherein the jaw actuating structure includes a member coupled with the ram assembly and a linkage between the member and at least one of the jaws, such that movement of the member moves the at least one jaw via the linkage. 
   
   
     8. The tool of  claim 1 , wherein the spring structure is a constant rate compression spring. 
   
   
     9. The tool of  claim 5 , further comprising at least one roller between the gear rack and the body to permit the gear rack to move in a controlled manner with respect to the body. 
   
   
     10. The tool of  claim 7 , further comprising at least one roller between the gear rack and the body to permit the gear rack to move in a controlled manner with respect to the body. 
   
   
     11. The tool of  claim 1 , further comprising a fourth check valve between the pump chamber and the ram chamber, the fourth check valve being constructed and arranged to permit fluid, under certain pressure conditions to pass from the pump chamber to the ram chamber. 
   
   
     12. The tool of  claim 1 , wherein the trigger and the lever are each constructed and arranged to be moved manually by hand. 
   
   
     13. A hydraulically powered and operated tool comprising:
 a body, 
 trigger means mounted for movement between first and second positions with respect to the body, 
 a pair of jaws mounted with respect to the body so that at least one of the jaws is movable between an opened jaw position and a closed jaw position so as to engage work between the jaws, 
 means for moving the at least one jaw, 
 a ram assembly having first and second ends and including a valve actuating structure and a ram piston, the valve actuating structure having first and second ends, the first end of the ram assembly being coupled with the means for causing movement of the at least one jaw, 
 a first means for controlling fluid flow associated with the ram piston, 
 a second means for controlling fluid flow associated with the ram piston and with the second end of the valve actuating structure, 
 means, associated with the first end of the valve actuating structure and with the ram assembly, for initiating tool operation, 
 surfaces defining a cavity in the body, the cavity having hydraulic fluid therein, the ram piston being disposed in the cavity separating the cavity to define a ram chamber and a reservoir chamber, 
 means, engaging a second end of the ram assembly, for biasing the ram assembly, and 
 a pump assembly operatively associated with the trigger means to be movable between a first position, when the trigger means is in the first position, and a second position when the trigger means is in a second position, the pump assembly having a pump chamber in selective fluid communication with the ram chamber and the reservoir chamber, 
 whereby, 1) when the means for initiating tool operation is moved to an activated position, the valve actuating structure unseats the second means for controlling fluid flow permitting fluid to flow from the ram chamber to the reservoir chamber, with the ram assembly displacing fluid as it compresses the means for biasing and causes the means for moving at least one jaw to move at least one jaw so work can be placed between the jaws, and 2) when the means for initiating tool operation is released from the activated position, the second for controlling fluid flow is seated and the means for biasing drives the ram assembly to an extended position causing the means for moving at least one jaw to move the at least one jaw so the jaws engage the work, with the first means for controlling fluid flow being unseated by fluid pressure in the reservoir chamber, permitting fluid to flow from the reservoir chamber to the ram chamber, and 3) when the trigger means is moved from the first position to the second position, the pump assembly moves to the second position thereof and forces fluid from the pump chamber into the ram chamber causing the first means for controlling fluid flow to seat, with the forced fluid being exerted on the ram piston, increasing force of the jaws on the work. 
 
   
   
     14. The tool of  claim 13  wherein the valve actuating structure is a push rod and the second mean for controlling fluid flow includes a ball valve associated with the ram piston, such that when the means for initiating tool operation is moved to engage the push rod, the push rod moves and unseats the ball valve permitting fluid to flow past the ram piston, and when the means for initiating tool operation is released, a spring biases the ball valve to a seated position. 
   
   
     15. The tool of  claim 13 , wherein the pump assembly includes:
 a pump piston in the pump chamber, the pump piston having a first diameter portion and a second diameter portion that is larger than the first diameter portion, the trigger means being connected to the pump piston, and 
 a third means for controlling fluid flow permitting, under certain conditions, fluid to flow from the reservoir chamber to the pump chamber, and under different conditions, preventing fluid flow from the pump chamber to the reservoir chamber, 
 whereby, as the trigger means is moved to the second position, the pump chamber changes volume due to the second diameter portion of the pump piston replacing the first diameter portion in the pump chamber, causing fluid to be forced into the ram chamber, and when the trigger means is moved to the first position, fluid moves from the reservoir chamber to the pump chamber. 
 
   
   
     16. The tool of  claim 13 , wherein the ram piston is movably disposed in a bore in the body, and wherein the first means for controlling fluid flow is a check valve including an O-ring disposed between a peripheral surface of the ram piston and surfaces defining the bore. 
   
   
     17. The tool of  claim 13 , wherein the means for moving at least one jaw includes a gear rack and first and second gear segments, the gear rack being coupled with the ram assembly, the first gear segment being engaged with the gear rack, the second gear segment being associated with at least one of the jaws, the first and second gear seconds being engaged with each other such that movement of the gear rack moves the at least one jaw. 
   
   
     18. The tool of  claim 15 , further including at least one link connecting the pump piston to the trigger means. 
   
   
     19. The tool of  claim 13 , wherein the means for moving at least one jaw includes a member coupled with the ram assembly and a linkage between the member and at least one of the jaws, such that movement of the member moves the at least one jaw via the linkage. 
   
   
     20. The tool of  claim 13 , wherein the means for biasing includes a constant rate compression spring. 
   
   
     21. The tool of  claim 17 , further comprising at least one roller between the gear rack and the body to permit the gear rack to move in a controlled manner with respect to the body. 
   
   
     22. The tool of  claim 19 , further comprising at least one roller between the gear rack and the body to permit the gear rack to move in a controlled manner with respect to the body. 
   
   
     23. The tool of  claim 13 , further comprising a check valve between the pump chamber and the ram chamber, the check valve being constructed and arranged to permit fluid, under certain pressure conditions to pass from the pump chamber to the ram chamber. 
   
   
     24. The tool of  claim 13 , wherein the trigger means and the means for initiating tool operation are each constructed and arranged to be moved manually by hand. 
   
   
     25. A hydraulic powered and operated tool comprising:
 a body, 
 a pair of jaws mounted with respect to the body so that at least one of the jaws is movable between an opened jaw position and a closed jaw position so as to engage workpiece between the jaws, 
 a ram assembly disposed in the body and operatively associated with the jaws, 
 first means for causing the ram assembly to move thereby causing the jaws to initially engage the workpiece with a first force, and 
 second means for exerting fluid on the ram assembly to move the ram assembly further, causing the jaws to exert a second force, greater than the first force, on the workpiece. 
 
   
   
     26. The tool of  claim 25 , wherein the first means is a constant rate compression spring. 
   
   
     27. The tool of  claim 25 , wherein the second means is a pump assembly provided in the body and constructed and arranged to supply the fluid that is exerted on ram assembly. 
   
   
     28. A method of applying force to workpiece, the method including:
 providing a hydraulic tool having a pair of jaws constructed and 
 arranged to receive the workpiece there-between, the tool including a ram assembly operatively associated with the jaws, 
 causing the ram assembly to move thereby causing the jaws to initially engage the workpiece with a first force, and 
 exerting fluid on the ram assembly to cause the ram assembly to move further, causing the jaws to exert a second force, greater than the first force, on the workpiece. 
 
   
   
     29. The method of  claim 28 , wherein the ram assembly is caused to move at a first speed to initially engage the workpiece, and the ram assembly is caused to move by the fluid at a second speed less than the first speed. 
   
   
     30. The method of  claim 28 , wherein the step of causing the ram assembly to move to cause the jaws to initially engage the workpiece includes permitting spring structure, coupled with the ram assembly, to drive the ram assembly. 
   
   
     31. The method of  claim 28 , wherein the step of exerting fluid includes using a pump assembly in the tool to supply the fluid that is exerted on the ram assembly. 
   
   
     32. The method of  claim 31 , wherein the step of using a pump assembly includes actuating the pump assembly by manually moving a trigger associated with the pump assembly.